Nias has an ergative–absolutive alignment.[5] Unusually, it appears to be the absolutive (mutated) case which is marked, against the near-universal tendency to mark the ergative.[6]

There are no adjectives in Nias, with that function taken by verbs.[5]

Nias shows consonant mutation at the beginning of nouns and some other classes of words to show grammatical case. Several consonants are subject to mutation as shown in the table below. Where a word begins in a vowel, either n or g is added before the vowel; the choice of n or g is lexically conditioned. (For example, öri ~ nöri is 'village federation', öri ~ göri is 'bracelet'.)[5]

Initial mutations

Base form

Mutated form

f

v

t

d

s

z

c

k

g

b

mb

d

ndr

vowel

n + vowelg + vowel

Other consonants do not change.

The unmutated form is used in citation. The mutated form only occurs on the first noun in a noun phrase (that is, not after a conjunction like 'and'). It is used for:

absolutive case (with a transitive verb, only in a main clause; with an intransitive verb, also in dependent clauses)